Physics – Optics
Scientific paper
Dec 2001
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001eso..presp..37.&link_type=abstract
ESO Press Release, 12/2001
Physics
Optics
Scientific paper
VLT ISAAC Looks for Young Stars in the Famous "Pillars of Creation"
Summary
Through imaging at infrared wavelengths, evidence has been found for recent star formation in the so-called "Pillars of Creation" in the Eagle Nebula (also known as Messier 16 ), made famous when the NASA/ESA Hubble Space Telescope (HST) obtained spectacular visible-wavelength images of this object in 1995.
Those huge pillars of gas and dust are being sculpted and illuminated by bright and powerful high-mass stars in the nearby NGC 6611 young stellar cluster . The Hubble astronomers suggested that perhaps even younger stars were forming inside.
Using the ISAAC instrument on the VLT 8.2-m ANTU telescope at the ESO Paranal Observatory , European astronomers have now made a wide-field infrared image of the Messier 16 region with excellent spatial resolution, enabling them to penetrate the obscuring dust and search for light from newly born stars .
Two of the three pillars are seen to have very young, relatively massive stars in their tips. Another dozen or so lower-mass stars seem to be associated with the small "evaporating gaseous globules (EGGs)" that the Hubble astronomers had discovered scattered over the surface of the pillars.
These findings bring new evidence to several key questions about how stars are born . Was the formation of these new stars triggered as the intense ultraviolet radiation from the NGC 6611 stars swept over the pillars, or were they already there? Will the new stars be prematurely cut off from surrounding gas cloud, thus stunting their growth? If the new stars have disks of gas and dust around them, will they be destroyed before they have time to form planetary systems?
PR Photo 37a/01 : Full wide-field ISAAC image of the Eagle Nebula. PR Photo 37b/01 : Close-up view of the ISAAC image , showing the famous "Pillars of Creation". PR Photo 37c/01 : Enlargement of the head of Column 1 . PR Photo 37d/01 : Enlargement of the head of Column 2 . PR Photo 37e/01 : Enlargement of the head of Column 4 . PR Video Clip 08a/01 : A "dissolve" between the Hubble visible wavelength and VLT infrared views of the pillars. PR Video Clip 08b/01 : Hubble and VLT views of the head of Column 1 . The famous "Pillars of Creation"
Hundreds of millions of people all over the world have admired those towering "Pillars of Creation" in Messier 16 (M16) , also known as the Eagle Nebula , and located in the southern constellation of Serpens. It is one of the most famous NASA/ESA Hubble Space Telescope (HST) images - released in 1995, it has become an icon of modern astronomy, giving the viewer an extraordinary three-dimensional impression of scuba-diving through some leviathan undersea forest. These light-years long columns of gas and dust are being simultaneously sculpted, illuminated, and destroyed by the intense ultraviolet light from massive stars in the adjacent NGC 6611 young stellar cluster . Within a few million years, a mere twinkling of the universal eye, they will be gone forever.
But before they are, they have a chance to leave a longer-lasting legacy: a whole new generation of stars may be forming within them. Their formation may have been triggered by the immense power of the NGC 6611 stars, or perhaps they had already started to form quietly earlier on, only to be suddenly subjected to the ravages of an ionising storm front.
The real question is then: are there or are there not any new born stars inside those "Pillars of Creation"? The Hubble Space Telescope view
When the HST turned to photograph M16 in 1995, it did so using its visible wavelength camera, WFPC-2 . The Hubble astronomers [1] took data through three narrow-bandpass optical filters selecting emission lines from the ionised gas they knew to be present in the region. In doing so, they obtained an extraordinarily sharp view of the well-known pillars of cold gas and dust that are sometimes referred to as "elephant trunks" for obvious reasons.
Their image showed the light-years long pillars partly silhouetted against a bright nebular background, and revealed in exquisite detail the surface structure of the pillars as they are being transformed by ultraviolet radiation from massive, hot stars in the NGC 6611 cluster which lies just outside the area covered by the Hubble image.
A surprising finding made by the Hubble astronomers was that the pillars are covered with a large number (they counted 73) of small bumps and protrusions which in a few cases are almost completely detached from the pillars. With a typical angular size of only 0.5 arcsec, those objects had not been seen in previous ground-based photographs, and it took the exceptional acuity of Hubble to reveal them.
The astronomers dubbed these objects "evaporating gaseous globules" , shortened to "EGGs" . They noted that one or two of these EGGs appeared to have stars right at their tips, and they suggested that perhaps the EGGs are formed as the advancing front of ionised gas driven by the hot NGC 6611 stars is slowed down by the presence of dense knots of gas and dust within the larger pillars. Within those knots then, they hypothesised a population of extremely young stars, still in the womb of their natal cloud but soon to be rudely exposed to a much harsher outside world.
However, there was a problem: since their images were taken at visible wavelengths which are relatively easily absorbed by the dust in the EGGs, the Hubble astronomers could not actually see inside the EGGs to test their theory. The VLT looks inside the "Pillars"
What was needed then was a survey of the M16 region made at longer wavelengths and penetrating much more deeply through the dense dust. Such a survey should be sensitive enough to detect faint, low-mass young stars deeply embedded in the dusty EGGs. It should have excellent sub-arcsec angular resolution to unambiguously identify an object with a given EGG. And it should cover a wide field-of-view to probe all of the pillars and their surroundings.
Over the past twenty years, a number of surveys of M16 have been made at near-infrared, mid-infrared, and millimetre wavelengths. Unfortunately, none of them had this perfect combination of characteristics to answer the crucial question of whether or not there is a population of young stars inside the Eagle's EGGs .
However, this past austral autumn (April and May 2001), European astronomers [2] were able to image the Eagle Nebula at near-infrared wavelengths , using the infrared multi-mode ISAAC instrument on the 8.2-m VLT ANTU telescope at ESO's Paranal Observatory in Chile. By specifying that the observations be carried out in so-called "service mode", they ensured that the on-site ESO team could undertake their pre-defined programme under the necessary excellent observing conditions.
The results were well worth the effort! The ISAAC near-infrared images cover a 9 x 9 arcmin region, i.e., fourteen times the area seen in the famous Hubble visible image, in three broad-band colours and with sufficient sensitivity to detect young stars of all masses and - most importantly - with an image sharpness as good as 0.35 arcsec. Although this is still some way from the diffraction-limited performance of 0.07 arcsec or better that is now achieved with the adaptive optics system NAOS/CONICA on the VLT telescope (cf. ESO PR 25/01 ), the ISAAC data cover a much wider field-of-view and, vitally, with enough image resolution to probe deep into the individual EGGs . The ISAAC infrared images of Messier 16
ESO PR Photo 37a/01
ESO PR Photo 37a/01
[Preview - JPEG: 400 x 471 pix - 136k] [Normal - JPEG: 800 x 942 pix - 1.2M] [HiRes - JPEG: 3000 x 3532 pix - 12.9M]
Caption : ESO PR Photo 37a/01 is a three-colour composite mosaic image of the Eagle Nebula (Messier 16) , based on 144 individual images obtained with the infrared multi-mode instrument ISAAC on the ESO Very Large Telescope (VLT) at the Paranal Observatory. At the centre, the so-called "Pillars of Creation" can be seen. This wide-field infrared image shows not only the central three pillars but also several others in the same star-forming region, as wel
No affiliations
No associations
LandOfFree
The Eagle's EGGs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Eagle's EGGs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Eagle's EGGs will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1103134